1. Field of the Invention
The present invention relates to integrated circuit (IC) devices, and in particular to a semiconductor device and a method for fabricating the same.
2. Description of the Related Art
Recently, due to the rapid development of communication devices such as mobile communication devices and personal communication devices, wireless communication products such as mobile phones and base stations have been greatly developed. In wireless communication products, high-voltage elements of lateral double diffused metal-oxide-semiconductor (LDMOS) devices are often used as radio frequency (RF, 900 MHz-2.4 GHz) related elements therein.
LDMOS devices not only have a higher operating frequency, but they are also capable of sustaining a higher breakdown voltage, thereby having a high output power so that they can be used as power amplifiers in wireless communication products. In addition, due to the fact that LDMOS devices can be formed by conventional CMOS fabrication processes, LDMOS devices can be fabricated from a silicon substrate which is relatively cost-effective and employs mature fabrication techniques.
For RF applications, the LDMOS devices require low gate to drain capacitance to enhance the maximum operating frequency thereof. In addition, the LDMOS devices also require low source to drain resistance (Ron). However, to get low Ron, the drift region and the gate interface of the LDMOS devices need to be increased, which will increase the gate to drain capacitance. Therefore, improved LDMOS devices with both low gate to drain capacitance and low source to drain resistance (Ron) are desired.